Display screen or a portion thereof with transitional graphical user interface



FIG. 1 is a first image in the sequence of a display screen or a portion thereof with transitional graphical user interface showing my new design;

FIG. 2 is second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof;

FIG. 5 is a fifth image thereof; and,

FIG. 6 is a sixth image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-6. The process or period in which one image transitions to another image forms no part of the claimed design.

The broken lines in FIGS. 1-6 showing the display screen or a portion thereof and graphical user interface represent portions that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or a portion thereof with transitional graphical user interface, as shown and described. 